The run time of unmanned air systems (UAS) aka drones is limited by their power sources. State of the art UAS use light-weight lithium ion/polymer batteries with specific energies that range from ˜200-300 Wh/kg, enabling flight times on the order of 20-60 min. Emerging applications including infrastructure inspection (e.g. roads, bridges, power lines, rail, pipelines, etc) and package delivery may be desired to have greater flight times on a battery charge. In some instances, greater than six-hour flight times are desired in order for such as UAS to be commercially viable.
Efficient energy storage and utilization faces many obstacles. Proton exchange membrane (PEM) fuel cells for man-portable power and micro air vehicles require light-weight, small-size, and high-rate hydrogen sources. Commercially available hydrogen sources such as metal hydrides, compressed hydrogen in cylinders, or catalytic water borohydride hydrogen generators are capable of high rate hydrogen generation, but are heavy and bulky.
While some hydrogen generators are light-weight and have small size, they are incapable of generating hydrogen at a sufficiently high rate for many applications.